diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a2fe0065983..d5f89bee8bf 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -852,7 +852,8 @@ namespace ts {
 
             if (!result) {
                 if (nameNotFoundMessage) {
-                    if (!checkAndReportErrorForMissingPrefix(errorLocation, name, nameArg)) {
+                    if (!checkAndReportErrorForMissingPrefix(errorLocation, name, nameArg) &&
+                       !checkAndReportErrorForExtendingInterface(errorLocation, name)) {
                         error(errorLocation, nameNotFoundMessage, typeof nameArg === "string" ? nameArg : declarationNameToString(nameArg));
                     }
                 }
@@ -936,6 +937,25 @@ namespace ts {
             return false;
         }
 
+
+        function checkAndReportErrorForExtendingInterface(errorLocation: Node, name: string): boolean {
+            if (!errorLocation || errorLocation.kind !== SyntaxKind.Identifier ||
+                !errorLocation.parent || !errorLocation.parent.parent ||
+                errorLocation.parent.parent.kind !== SyntaxKind.HeritageClause) {
+                return false;
+            }
+            const heritageClause = <HeritageClause>errorLocation.parent.parent;
+            if (heritageClause.token !== SyntaxKind.ExtendsKeyword) {
+                return false;
+            }
+            const enclosingScope = heritageClause.parent.parent.locals;
+            if (enclosingScope && getSymbol(enclosingScope, name, SymbolFlags.Interface)) {
+                error(errorLocation, Diagnostics.Cannot_extend_an_interface_0_Did_you_mean_implements, name);
+                return true;
+            }
+            return false;
+         }
+
         function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void {
             Debug.assert((result.flags & SymbolFlags.BlockScopedVariable) !== 0);
             // Block-scoped variables cannot be used before their definition
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index b78c342481f..30a4e1575e5 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1935,6 +1935,10 @@
         "category": "Error",
         "code": 2688
     },
+    "Cannot extend an interface '{0}'. Did you mean 'implements'?": {
+        "category": "Error",
+        "code": 2689
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000